axVec {FITSio} | R Documentation |
axVec
generates a vector of axis values from variables
contained in a FITS image file header.
axVec(nax = 1, axDat)
nax |
index number of the axis. |
axDat |
data table axis variables produced by
readFITSarray (which is also contained in readFITS ). |
Run once for each axis needed.
A vector with length equal to the number of pixels along the axis. Vector values v are:
v = (1 - CRPIXn times CDELTn) + CRVALn
where CRPIXn, CDELTn, and CVALn are the reference pixel, pixel increment, and reference pixel value for each axis n, following the FITS standard.
Andrew Harris
Hanisch et al., Astron. Astrophys. 376, 359-380 (2001)
require("FITSio") Z <- matrix(1:15, ncol = 3) writeFITSim(Z, file = 'test.fits', c1 = 'Test FITS file', crpix = c(1,1), crvaln = c(10, 100), cdeltn = c(8, 2), ctypen = c('Distance', 'Time'), cunitn = c('Furlongs', 'Fortnights')) X <- readFITS('test.fits') ax1 <- axVec(1, X$axDat) ax2 <- axVec(2, X$axDat) xlab <- X$axDat$ctype[1] ylab <- paste(X$axDat$ctype[2], " [", X$axDat$cunit[2], "]", sep = "") image(ax1, ax2, X$imDat, xlab = xlab, ylab = ylab) unlink("test.fits")